Strategies to improve the outcome of stem cell transplantation in multiple myeloma.

Multiple myeloma (MM) is an incurable hematological malignancy with an average survival of 3 years with conventional therapy. Allogeneic hematopoietic cell transplantation (allo-HCT) may cure some patients, but has been associated with a very high transplantation-related mortality (TRM) of over 40%.(1) In contrast to allo-HCT, autologous hematopoietic cell transplantation (AHCT) has been much safer, with a TRM <3% in the 1990s. Therefore, in the last 15 years AHCT has become a common procedure for MM patients. The widespread use of AHCT has been associated with a median survival of 55-72 months,(2,3,4,5,6) and two large randomized trials have shown that AHCT is superior to conventional chemotherapy for the treatment of MM.(3,7) Approaches to improve the outcome of stem cell transplantation for MM patients include consideration of patient status, efficacy and toxicity of induction therapy, source of hematopoietic rescue, conditioning regimens, and maintenance therapy. Recent attempts to improve outcome include tandem AHCT, AHCT followed by RIC (reduced intensity conditioning) allo-HCT, and allo-HCT with T-cell depletion and subsequent donor-lymphocyte infusions (DLI), while novel therapies and improved supportive care may improve the overall survival (OS) of all MM patients with or without transplantation.